The invention relates to a device and a method for diverting items which are transported on a conveyor. The items are pushed down from the conveyor by means of a diversion device which has one or more diversion segments, which can be moved along with the conveyor for a section and individually extended across the direction of transport.
Such devices are used e.g. in drinks filling plants to sort out defective containers, e.g. glass bottles, or incompletely filled or incorrectly closed containers. Such devices are known from CA-A-985213 and U.S. Pat. No. 3,791,518. The diversion segments are able to be displaced and are guided along a continuous track, being guided parallel and synchronously to the conveyor and guided back underneath the conveyor or laterally offset thereto. The extension of the individual diversion segments across the direction of transport takes place by a link motion.
A device is known from EP-A-0 003 111, for the lateral deflection of items which are transported on a conveyor, in which the deflection device is divided into a number of deflection segments which together form a continuous deflecting surface and can be individually extended. The items to be deflected are diverted along a fixed deflecting surface. They are then forcibly braked and light items in particular such as empty drinks bottles can thereby fall over. If the items are travelling in close succession, braking of the item to be diverted can also lead to accumulations of the following items.
The object of the invention is to reduce the mechanical expenditure which is necessary for the diversion of items which are transported on a conveyor.
Within the framework of the device according to the invention, this object is achieved in that the diversion segment(s) is (are) guided side by side in a carriage in the direction of transport and the carriage can be moved to and fro in the direction of transport.
The carriage is preferably controlled such that it runs along for a section roughly synchronously with the conveyor, the length of the section, along which the carriage runs synchronously with the direction of transport being shorter than the distance between the first and the last of the diversion segments guided in the carriage plus the minimum distance between the items.
Within the framework of the method according to the invention this object is achieved in that the diversion segments are arranged side by side in a carriage in the direction of transport, the carriage can be moved to and fro in the direction of transport, the length of the section along which the carriage moves with the conveyor is shorter than the distance between the first and the last of the diversion segments inside the carriage plus the minimum distance between the items, namely by the distance by which the conveyor moves on during the backward movement of the carriage, and the items are pushed in groups off the conveyor, each group beginning with a first item to be diverted and including all further items to be diverted which follow the first item to be diverted within a section the length of which equals the length of the movement of the carriage accompanying the conveyor.
The advantages that can be achieved through the invention consist in particular of the fact that a long, smooth diversion curve can be achieved through the synchronous movement of the diversion segments relative to the conveyor. The movement of the diversion segments in the direction of transport (X-direction) and across it (Y-direction) can be controlled separately so that both movement components are decoupled. The diversion curve can therefore be controlled without mechanical modifications and can be adapted to the stability, the weight or such other features of the items as well as to the speed of the conveyor. When there are no items to be diverted, then the carriage remains in its at-rest position, whereby wear is reduced compared with the diversion devices named at the beginning with synchronously running diversion segments guided on a continuous track.
The carriage can be guided to and fro in a frame in the direction of transport. The carriage is moved from an initial position at roughly the same speed as the conveyor alongside the conveyor (X-direction), so that during this forward movement of the carriage each diversion segment runs along essentially with a certain point of the conveyor and, by extending the diversion segment across the direction of transport (Y-direction), a container standing at this point can be pushed off the conveyor. All items to be diverted which are located within the length of the carriage are preferably pushed down simultaneously from the conveyor. The items transported on the conveyor are thus processed in groups. At the end of the forward movement, the carriage is returned to the initial position on the same path. The section covered by the synchronous forward movement is shorter than the distance between the first and the last diversion segment plus the minimum distance between the items by at least the piece by which the conveyor moves further within the time required for the return movement and to accelerate and brake the carriage.
This movement of the carriage is preferably controlled such that the carriage is at rest at the start or end of the diversion section. If there are one or more items to be diverted in the stream of items then the carriage initially moves, if it is in its at-rest position at the end of the diversion section, to the start of the diversion section. At the start of the diversion section the acceleration process is controlled such that the foremost diversion segment in the direction of transport reaches a position which is exactly congruent with the first item to be diverted. It is thereby guaranteed that the maximum number of diversion segments can be used for any following items to be diverted.
The extension movement (Y-direction) of the diversion segments and the choice of the diversion segments which are to be extended to divert the ascertained items, are particularly easy to carry out mechanically. The diversion segments can in general be extended and retracted in a horizontal direction. A vertically displaceable pin can be guided in the diversion segments, which projects upwards and downwards from the diversion segment. During the forward movement of the carriage a rail with a C profile which is open underneath is simultaneously moved back and forth in the Y-direction at a small distance above the diversion segments. The rail grips all the pins which are located in their upper position and thereby extends and again retracts the corresponding diversion segments during the forward movement of the carriage so that the front end of the diversion segments roughly describes a sine curve. The individual diversion segments are preferably chosen or activated during the return movement of the carriage. A single activator is sufficient for this, which is arranged underneath the carriage and presses the pins of the diversion segments, which are extended or retracted during the following forward movement, into the upper position. This can be effected by a lifting magnet, an air cylinder or an air jet. The use of an air jet as an activator is particularly easy. To this end, the lower end of the pins is somewhat widened to offer the air jet sufficient engagement surface.
If the time necessary for controlling and activating the individual pins noticeably slows down the return movement, then two activators can also be provided which are alternately assigned to the diversion segments so that the one activator activates the odd, and the other activator the even, diversion segments. There is also the possibility of extending and retracting each diversion segment by means of its own drive, e.g. a pneumatic cylinder. This would make the activators surplus. Although the device thereby becomes more expensive, this allows the diversion segments to be extended to varying degrees and the items to thus be diverted onto various paths.
The rail movable in Y-direction can be mounted on the carriage itself so that it also moves along with the carriage in X-direction, or it can be guided on the same frame as the carriage, the upper ends of the pins then sliding in the rail in X-direction. The latter design is mechanically simpler, as the drive for the Y-movement of the rail is then not carried by the carriage, but by the frame. A greater working speed also results from the lesser weight of the carriage.
The movement of the carriage and the movement of the rails are preferably each effected by a servo- or stepped motor via a chain or toothed belt, so that the position of the carriage and the rail can be exactly controlled at any time. The diversion curve on which the front end of an extended diversion segment engaging with the items moves can thereby be controlled precisely. A smooth diversion curve is preferred, i.e. smooth engagement with the items, relatively quick pushing-over of the items from the conveyor for example onto another conveyor running parallel to it, so that the items at no time lose contact with the diversion segment and thereby become labile. This is of particular importance for empty drinks bottles. Through this form of the diversion curve, the contact between the diversion segment and the item is furthermore gently broken, so that any eventual tipping back of the items is largely prevented here too. The diversion segments can thereafter be retracted as quickly as possible. At the end of the diversion movement of the carriage the pins of the individual segments are all brought into their lower position or other non-activation position. This can occur e.g. through a short downward movement of the rail.
The diversion onto various paths can also be effected by several devices arranged on or above the carriage, such as the previously mentioned rail, which move to and fro in Y-direction. The diversion segments are clicked into one of the devices during activation, according to the desired diversion curve. Various diversion routes can also be achieved by means of an individual device moving in Y-direction, each diversion segment having several activating pins, which then automatically disengage again at various extending positions and thereby lead to diversion paths of varying width.
Another possibility for activating the diversion segments is to house the diversion segments swivellable on an axis which is housed on the carriage pointing in X-direction and movable in Y-direction. In their at-rest, initial or non-activation position, all the diversion segments are directed vertically upwards and are held in this position by holding means, for example permanent magnets. To activate, the diversion segments concerned are detached from the holding means by air jets or strikers, so that they turn downwards in the horizontal. This choice or activation occurs again expediently during the return movement of the carriage. The axis can be moved forward and back in Y-direction similarly to the rail mentioned in the previous example and is located in the withdrawn position during the return movement of the carriage. During the diversion process, i.e. during the movement of the carriage in X-direction, the axis with the activated, horizontal and the non-activated, vertical diversion segments housed on it moves forward so that the activated, horizontal diversion segments engage with the items concerned and divert them. At the end of the diversion section, all the diversion segments are swivelled back into their at-rest position. This can occur for example by means of a linearly displaceable deactivation rail which extends parallel to the axis and engages with downward-directed extensions of the diversion segments. The deactivation rail can also be swivellable about the axis. To this end, radial fingers which entrain the diversion segments can also project from the axis and the axis can be rotatably housed so that, through a simple 90xc2x0 rotation of the axis, the horizontally directed diversion segments can be tilted into their vertical at-rest position again.
The movement in Y-direction need not be rectilinear. It can also be a rotation movement by means of a shaft mounted in a fixed manner, i.e. not movable forwards and backwards, on the carriage. Activation of the diversion segments can also involve a coupling of the diversion segments concerned for a diversion process with the shaft in a rotation-resistant manner and the carrying out by the shaft of a rotation of for example 30xc2x0 overall during the movement of the carriage in X-direction. In order that the ends of the diversion segments engaging with the items perform an horizontal as possible a movement, the shaft is to be arranged vertically above the path of the items.
The width of the individual diversion segments is preferably less than half the size of the items in the direction of transport, thus for drinks bottles half the diameter of the bottles. In this way, the vertex can be gripped in each case even when round items are travelling in close succession, by if necessary extending two successive diversion segments and thus preventing the item from slipping off from the segment. This means that either one or more diversion segments can be extended according to the relative position between item and diversion segment.
In the special situation where the items are transported in fixed grid, it is sufficient to provide a few segments in the same grid on the carriage. Such a situation occurs e.g. if drinks bottles are supplied by a screw conveyor or a star wheel and thereby stand in a fixed grid. The carriage then only needs to be provided with wide diversion segments corresponding to the grid.
The device according to the invention can also be used for so-called routing systems, in which items are distributed in groups onto a second transport device. It can be expedient in this case to provide one very wide diversion segment and a small number of narrower diversion segments, whereby the number of the items to be displaced can be chosen or adapted in each individual case.
Through the precise controllability of the extension and retraction movements of the diversion segments, e.g. more stable containers can be diverted at a greater speed so that they obtain a higher kinetic energy and do not come to a standstill immediately after being lifted or removed from the diversion segments, but move further along the conveyor in the diversion direction, because of their higher kinetic energy, after being lifted or removed from the diversion segments. The items can thereby be pushed as a whole further, across the direction of transport, than the extension width of the diversion segments.
In certain cases even a single diversion segment is sufficient for the diversion of items, e.g. if there is a space between the items. A single diversion segment can be sufficient especially if the items are very stable and thus can be greatly accelerated in Y-direction so that because of their inertia, they move even further in Y-direction after being lifted or detached from the diversion segment. Through the uncoupling of the X- and the Y-drive, different pulses can be imparted to individual items in Y-direction, so that a targeted distribution of the items onto several diversion paths is possible. The minimum distance between the items is determined by the diversion time and return time of the diversion segment. When using two or more diversion segments, the minimum distances between the items can be correspondingly smaller, the diversion curve can be flatter or the transport speed can be areater.
Finally, there is also the possibility to use two or more such carriages, used alternately in each case, instead of one carriage movable in X-direction. The carriages are arranged at different positions along the conveyor. The section along which each carriage can be moved to and fro in the direction of transport can also be longer than the distance between the first and the last diversion segment plus the minimum distance between the items of the carriage concerned. The several carriages can also be arranged vertically one above the other. The version with several carriages is particularly interesting for versions with a single diversion segment per carriage. Diversions onto several diversion paths are simplified where there are several diversion segments for each carriage.
There are various possibilities for the activation of the diversion segments. In addition to the already mentioned activation by pins, it is also possible to unfold the diversion segments for activation or to extend them from above or below into an activating position and then to start the diversion process again.
A very simplified possibility for a solid procedure for the diversion movement in Y-direction results from the use of a securely attached curve element through which the pins located in the activating position are guided. Separate drive for the movement of a rail in Y-direction can then be dispensed with. Another possibility is to connect the rails of the Y-drive to the X-drive via a curve control.
The front engagement surfaces can be both smooth and specially shaped, for example to support particularly labile items or containers. The front ends of the diversion segments can also be provided with suction cups which are correspondingly controlled to secure the containers during the diversion process and later release them again. Particularly labile items can also be guided between the diversion segments by two diversion segments directed against towards each other, the diversion devices of the conveyor sides facing each other being arranged. Another possible solution is to extend the diversion segments from the top downwards, each on the right- and left-hand side of an item, and to attach the diversion device above the items and then, after the diversion segments have been extended left and right, to displace these correspondingly in Y-direction and then to retract them again. In such versions, double diversions are also conceivable, the items then being fed centrally, the diversion segments dropping from above and the items being diverted by two rails or other devices for displacement in Y-direction in each case in one or the other direction.
In a special version, the front ends of the diversion segments can also be developed as a angle with one arm extending in the transport direction and one arm arranged at its front end across the direction of transport. The items then, as it were, run up against a stop and it is no longer necessary to move the carriage completely synchronously relative to the transport speed, but it can also travel at a reduced speed, so that neither an accumulation nor a guiding together of the items additionally takes place during the diversion process. It thereby becomes possible to guide together individual items which are arranged great distances apart on the first conveyor in a grid, onto a slower-running second conveyor for the diverted items. With suitably designed diversion segments, the carriage can also be moved at a greater speed than that of the conveyor, the items being able to be combined in groups.
Embodiments of the invention are explained in the following using the diagram. There are shown in:
FIG. 1 in plan view, an embodiment of the device for diverting items with displaceable diversion segments;
FIG. 2 the device of FIG. 1 in the section along 2xe2x80x942;
FIG. 3 in plan view an embodiment of the device with foldable diversion segments and
FIG. 4 the device of FIG. 4 in section along 4xe2x80x944.